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Full text of "Treatise On Analysis Vol-Ii"

284      XIV   INTEGRATION IN LOCALLY COMPACT GROUPS
for all s E K (3.16.5). Hence, for all x e V, we have

{*                                                                        r

I /(s-'*o) dn(s)  g 2 H/ll M(JK) + |

from which (ii) follows.

(iii) Again we may suppose that fi ^ 0. By hypothesis, for each e > 0,
there exists a compact subset H of G such that |/(x)| ^ e for all x ^ H. Take
K as in the proof of (ii) above, and suppose that x $ KH. Then if s e K we
H and therefore

JG-K

^ ll/ll '/

which proves that \JL */e

(14.9.3)    t?ery measure jn on G zj convolvable with every function f e jf~c(G);
r/ze integral on the right-hand side of (14.8.2) is defined for all x e G, awrf */ze
function x\-+j f(s~~1x) d^(s) is continuous on G.

Since the measure/- ft has compact support, p and/* ft are convolvable
(14.6.4), and it is clear that the integral tf(s~~1x) dfj,(s) is defined for all x G G.
The continuity of the function x*-*jf(s~lx) dfi(s) follows from (14.1.5.5).

We shall leave to the reader the task of stating the corresponding proposi-
tions for the convolution/* p. It should be noticed in particular that (14.9.2)
and its analog for/* /z prove that if G is unimodular (14.3), then S?g(G) is a
left and right module over the algebra M(G), and the external laws of com-
position of these two module structures are compatible by virtue of (14.7.2).

(14.9.4)    Let p, v be two measures on G, and let fe Jfc(G). Suppose that
ji and v are convolvable. Then the function n*fis v-integrable and

(14.9.4.1)                          </,/**v> = <Ai*/,v>.

Likewise, if p and v are bounded and feV$(G), the function /u */ is
continuous and bounded (hence v-integrable) and the formula (14.9.4.1) is valid.

For the hypothesis implies that the function (s9 x)\-*f(s~lx) is (^  v>
mtegrable, and the result therefore follows from the theorem of Lebesgue-
Fubini.should exist a ^-negligible set N such that the